If the existing sliding door roller rail is worn and the sliding door sticks and jams.

Horizontally level new rail is needed so the sliding door closes properly due to a worn sliding door track.

Even if a small portion of your rail is damaged, you need to cover the entire length of the door.

The 9/16" Stainless Steel Sliding Door Track Cover stands on the sliding door threshold, thereby giving a horizontally level new rail for the sliding door to slide on. It also supports the sliding door the entire length of the door track.